<?php
require_once './vendor/autoload.php';

$baidu = new \Kangcg\Baidu\Baidu([
    'secret' => 'tl0v8HjM8UsXqWemsGHgOLKioCO1i3LT',
    'appid' => '28937645',
    'appkey' => 'Ak5kyVTlrde5epeH8NVX7bjn',
]);

$result = $baidu->text->textOcrByPrecision('', 'https://images-na.ssl-images-amazon.com/captcha/tinytuux/Captcha_omwyubkpvz.jpg');

if(!$result){
    var_dump($baidu->getErrorMsg());
}

var_dump($result);